The invention concerns a nuclear magnetic resonance (NMR) spectrometer for investigating a liquid sample in a sample tube, in particular a glass sample tube, with a sample bushing having a bore into which one end of the sample tube is inserted with tight fit, wherein, in particular, the sample bushing is substantially cylindrical and the bore extends along the cylinder axis and wherein the sample bushing has at least one groove on its outer periphery.
An NMR spectrometer of this type is disclosed e.g. in the leaflet “Bruker's 1 mm MicroProbes, 400-600 MHz, Catalogue of Applications” of the company group Bruker BioSpin.
Nuclear magnetic resonance (NMR) spectroscopy is an effective method to analyze the structure of chemical compounds.
Since the available amount of sample is often very small, this sample amount is filled into measuring capillaries with an outer diameter of typically approximately 1 mm, which also saves space for storing the measuring samples.
Handling of microsamples is difficult due to the fragility of the measuring capillaries. For handling, the sample must be transported for NMR measurement to the region of high magnetic field, typically to the inside of a superconducting magnet coil, wherein high positioning accuracy is required.
There are conventional sample bushings (Bruker's 1 mm MicroProbes, 400-600 MHz, Catalogue of Applications) to prevent direct handling of the measuring capillaries. These measuring capillaries—or more generally a sample tube—is held in the sample bushing and only the sample bushing is directly handled during transport. The sample bushing is made from a sufficiently robust material, e.g. plastic material.
The sample bushing is handled manually using suitable tools, e.g. tweezers, to position the sample bushing, e.g. to introduce the sample bushing including sample tube from a container into a rotor or vice versa. This process requires great operator skill and is therefore very risky for the sample.
The sample glass is usually introduced into the measuring chamber of the NMR magnet by means of an air cushion, wherein this dynamic process is very critical and the sample glass can easily break, in particular when the sample bushing is heavy and therefore exerts large inertial forces onto the sample glass. For this reason, the sample bushing is conventionally provided with one or more grooves to reduce material and weight.
It is the underlying purpose of the present invention to present an NMR spectrometer which permits safe handling of a sample bushing including sample tube.